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authorAndrii Nakryiko <andrii@kernel.org>2021-08-15 00:05:59 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2021-08-17 00:45:07 +0200
commit7adfc6c9b315e174cf8743b21b7b691c8766791b (patch)
tree22e614432aca7e0c5eedceb7c4b74c6ce8bb4ef7 /kernel/trace
parent82e6b1eee6a8875ef4eacfd60711cce6965c6b04 (diff)
bpf: Add bpf_get_attach_cookie() BPF helper to access bpf_cookie value
Add new BPF helper, bpf_get_attach_cookie(), which can be used by BPF programs to get access to a user-provided bpf_cookie value, specified during BPF program attachment (BPF link creation) time. Naming is hard, though. With the concept being named "BPF cookie", I've considered calling the helper: - bpf_get_cookie() -- seems too unspecific and easily mistaken with socket cookie; - bpf_get_bpf_cookie() -- too much tautology; - bpf_get_link_cookie() -- would be ok, but while we create a BPF link to attach BPF program to BPF hook, it's still an "attachment" and the bpf_cookie is associated with BPF program attachment to a hook, not a BPF link itself. Technically, we could support bpf_cookie with old-style cgroup programs.So I ultimately rejected it in favor of bpf_get_attach_cookie(). Currently all perf_event-backed BPF program types support bpf_get_attach_cookie() helper. Follow-up patches will add support for fentry/fexit programs as well. While at it, mark bpf_tracing_func_proto() as static to make it obvious that it's only used from within the kernel/trace/bpf_trace.c. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210815070609.987780-7-andrii@kernel.org
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/bpf_trace.c35
1 files changed, 34 insertions, 1 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 57879d28f824..cbc73c08c4a4 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -975,7 +975,34 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
.arg1_type = ARG_PTR_TO_CTX,
};
-const struct bpf_func_proto *
+BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
+{
+ struct bpf_trace_run_ctx *run_ctx;
+
+ run_ctx = container_of(current->bpf_ctx, struct bpf_trace_run_ctx, run_ctx);
+ return run_ctx->bpf_cookie;
+}
+
+static const struct bpf_func_proto bpf_get_attach_cookie_proto_trace = {
+ .func = bpf_get_attach_cookie_trace,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
+BPF_CALL_1(bpf_get_attach_cookie_pe, struct bpf_perf_event_data_kern *, ctx)
+{
+ return ctx->event->bpf_cookie;
+}
+
+static const struct bpf_func_proto bpf_get_attach_cookie_proto_pe = {
+ .func = bpf_get_attach_cookie_pe,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
+static const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
@@ -1109,6 +1136,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
#endif
case BPF_FUNC_get_func_ip:
return &bpf_get_func_ip_proto_kprobe;
+ case BPF_FUNC_get_attach_cookie:
+ return &bpf_get_attach_cookie_proto_trace;
default:
return bpf_tracing_func_proto(func_id, prog);
}
@@ -1219,6 +1248,8 @@ tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_get_stackid_proto_tp;
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto_tp;
+ case BPF_FUNC_get_attach_cookie:
+ return &bpf_get_attach_cookie_proto_trace;
default:
return bpf_tracing_func_proto(func_id, prog);
}
@@ -1326,6 +1357,8 @@ pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_perf_prog_read_value_proto;
case BPF_FUNC_read_branch_records:
return &bpf_read_branch_records_proto;
+ case BPF_FUNC_get_attach_cookie:
+ return &bpf_get_attach_cookie_proto_pe;
default:
return bpf_tracing_func_proto(func_id, prog);
}

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